bpo-29762: More use "raise from None". (#569)
This hides unwanted implementation details from tracebacks.
diff --git a/Lib/_collections_abc.py b/Lib/_collections_abc.py
index 005d884..e89e84b 100644
--- a/Lib/_collections_abc.py
+++ b/Lib/_collections_abc.py
@@ -589,7 +589,7 @@
try:
value = next(it)
except StopIteration:
- raise KeyError
+ raise KeyError from None
self.discard(value)
return value
@@ -808,7 +808,7 @@
try:
key = next(iter(self))
except StopIteration:
- raise KeyError
+ raise KeyError from None
value = self[key]
del self[key]
return key, value
diff --git a/Lib/_weakrefset.py b/Lib/_weakrefset.py
index 7f9923c..4d0de8c 100644
--- a/Lib/_weakrefset.py
+++ b/Lib/_weakrefset.py
@@ -98,7 +98,7 @@
try:
itemref = self.data.pop()
except KeyError:
- raise KeyError('pop from empty WeakSet')
+ raise KeyError('pop from empty WeakSet') from None
item = itemref()
if item is not None:
return item
diff --git a/Lib/aifc.py b/Lib/aifc.py
index 13ad7dc..49a456a 100644
--- a/Lib/aifc.py
+++ b/Lib/aifc.py
@@ -149,25 +149,25 @@
try:
return struct.unpack('>l', file.read(4))[0]
except struct.error:
- raise EOFError
+ raise EOFError from None
def _read_ulong(file):
try:
return struct.unpack('>L', file.read(4))[0]
except struct.error:
- raise EOFError
+ raise EOFError from None
def _read_short(file):
try:
return struct.unpack('>h', file.read(2))[0]
except struct.error:
- raise EOFError
+ raise EOFError from None
def _read_ushort(file):
try:
return struct.unpack('>H', file.read(2))[0]
except struct.error:
- raise EOFError
+ raise EOFError from None
def _read_string(file):
length = ord(file.read(1))
diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index ee34996..f94ec92 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -1043,7 +1043,7 @@
except OSError as err:
raise OSError(err.errno, 'error while attempting '
'to bind on address %r: %s'
- % (sa, err.strerror.lower()))
+ % (sa, err.strerror.lower())) from None
completed = True
finally:
if not completed:
diff --git a/Lib/bdb.py b/Lib/bdb.py
index 67a0846..5a80fa8 100644
--- a/Lib/bdb.py
+++ b/Lib/bdb.py
@@ -336,11 +336,11 @@
try:
number = int(arg)
except ValueError:
- raise ValueError('Non-numeric breakpoint number %s' % arg)
+ raise ValueError('Non-numeric breakpoint number %s' % arg) from None
try:
bp = Breakpoint.bpbynumber[number]
except IndexError:
- raise ValueError('Breakpoint number %d out of range' % number)
+ raise ValueError('Breakpoint number %d out of range' % number) from None
if bp is None:
raise ValueError('Breakpoint %d already deleted' % number)
return bp
diff --git a/Lib/chunk.py b/Lib/chunk.py
index d94dd39..870c39f 100644
--- a/Lib/chunk.py
+++ b/Lib/chunk.py
@@ -64,7 +64,7 @@
try:
self.chunksize = struct.unpack_from(strflag+'L', file.read(4))[0]
except struct.error:
- raise EOFError
+ raise EOFError from None
if inclheader:
self.chunksize = self.chunksize - 8 # subtract header
self.size_read = 0
diff --git a/Lib/configparser.py b/Lib/configparser.py
index 230ab2b..ea971f3 100644
--- a/Lib/configparser.py
+++ b/Lib/configparser.py
@@ -1138,7 +1138,7 @@
sectiondict = self._sections[section]
except KeyError:
if section != self.default_section:
- raise NoSectionError(section)
+ raise NoSectionError(section) from None
# Update with the entry specific variables
vardict = {}
if vars:
diff --git a/Lib/copyreg.py b/Lib/copyreg.py
index 67f5bb0..ed29d71 100644
--- a/Lib/copyreg.py
+++ b/Lib/copyreg.py
@@ -70,7 +70,7 @@
except AttributeError:
if getattr(self, "__slots__", None):
raise TypeError("a class that defines __slots__ without "
- "defining __getstate__ cannot be pickled")
+ "defining __getstate__ cannot be pickled") from None
try:
dict = self.__dict__
except AttributeError:
diff --git a/Lib/difflib.py b/Lib/difflib.py
index 2095a5e..8296471 100644
--- a/Lib/difflib.py
+++ b/Lib/difflib.py
@@ -2079,7 +2079,7 @@
tag = {1: "- ", 2: "+ "}[int(which)]
except KeyError:
raise ValueError('unknown delta choice (must be 1 or 2): %r'
- % which)
+ % which) from None
prefixes = (" ", tag)
for line in delta:
if line[:2] in prefixes:
diff --git a/Lib/dis.py b/Lib/dis.py
index 0794b7f..f93d5b2 100644
--- a/Lib/dis.py
+++ b/Lib/dis.py
@@ -72,7 +72,7 @@
try:
tb = sys.last_traceback
except AttributeError:
- raise RuntimeError("no last traceback to disassemble")
+ raise RuntimeError("no last traceback to disassemble") from None
while tb.tb_next: tb = tb.tb_next
disassemble(tb.tb_frame.f_code, tb.tb_lasti, file=file)
diff --git a/Lib/json/decoder.py b/Lib/json/decoder.py
index 2422c6a..3741dee 100644
--- a/Lib/json/decoder.py
+++ b/Lib/json/decoder.py
@@ -103,7 +103,8 @@
try:
esc = s[end]
except IndexError:
- raise JSONDecodeError("Unterminated string starting at", s, begin)
+ raise JSONDecodeError("Unterminated string starting at",
+ s, begin) from None
# If not a unicode escape sequence, must be in the lookup table
if esc != 'u':
try:
diff --git a/Lib/json/scanner.py b/Lib/json/scanner.py
index 86426cd..c451eba 100644
--- a/Lib/json/scanner.py
+++ b/Lib/json/scanner.py
@@ -29,7 +29,7 @@
try:
nextchar = string[idx]
except IndexError:
- raise StopIteration(idx)
+ raise StopIteration(idx) from None
if nextchar == '"':
return parse_string(string, idx + 1, strict)
diff --git a/Lib/lib2to3/patcomp.py b/Lib/lib2to3/patcomp.py
index 06a4b9d..0fefa9a 100644
--- a/Lib/lib2to3/patcomp.py
+++ b/Lib/lib2to3/patcomp.py
@@ -59,7 +59,7 @@
try:
root = self.driver.parse_tokens(tokens, debug=debug)
except parse.ParseError as e:
- raise PatternSyntaxError(str(e))
+ raise PatternSyntaxError(str(e)) from None
if with_tree:
return self.compile_node(root), root
else:
diff --git a/Lib/lib2to3/pgen2/literals.py b/Lib/lib2to3/pgen2/literals.py
index 4f50d31..b9b63e6 100644
--- a/Lib/lib2to3/pgen2/literals.py
+++ b/Lib/lib2to3/pgen2/literals.py
@@ -29,12 +29,12 @@
try:
i = int(hexes, 16)
except ValueError:
- raise ValueError("invalid hex string escape ('\\%s')" % tail)
+ raise ValueError("invalid hex string escape ('\\%s')" % tail) from None
else:
try:
i = int(tail, 8)
except ValueError:
- raise ValueError("invalid octal string escape ('\\%s')" % tail)
+ raise ValueError("invalid octal string escape ('\\%s')" % tail) from None
return chr(i)
def evalString(s):
diff --git a/Lib/lib2to3/refactor.py b/Lib/lib2to3/refactor.py
index c5a1aa2..70b2a00 100644
--- a/Lib/lib2to3/refactor.py
+++ b/Lib/lib2to3/refactor.py
@@ -248,7 +248,7 @@
try:
fix_class = getattr(mod, class_name)
except AttributeError:
- raise FixerError("Can't find %s.%s" % (fix_name, class_name))
+ raise FixerError("Can't find %s.%s" % (fix_name, class_name)) from None
fixer = fix_class(self.options, self.fixer_log)
if fixer.explicit and self.explicit is not True and \
fix_mod_path not in self.explicit:
diff --git a/Lib/locale.py b/Lib/locale.py
index 73fc94d..5763b14 100644
--- a/Lib/locale.py
+++ b/Lib/locale.py
@@ -512,7 +512,8 @@
else:
return language + '.' + encoding
except (TypeError, ValueError):
- raise TypeError('Locale must be None, a string, or an iterable of two strings -- language code, encoding.')
+ raise TypeError('Locale must be None, a string, or an iterable of '
+ 'two strings -- language code, encoding.') from None
def getdefaultlocale(envvars=('LC_ALL', 'LC_CTYPE', 'LANG', 'LANGUAGE')):
diff --git a/Lib/mailbox.py b/Lib/mailbox.py
index 39f24f9..056251d 100644
--- a/Lib/mailbox.py
+++ b/Lib/mailbox.py
@@ -555,7 +555,7 @@
try:
return self._toc[key]
except KeyError:
- raise KeyError('No message with key: %s' % key)
+ raise KeyError('No message with key: %s' % key) from None
# This method is for backward compatibility only.
def next(self):
@@ -741,7 +741,7 @@
try:
return self._toc[key]
except KeyError:
- raise KeyError('No message with key: %s' % key)
+ raise KeyError('No message with key: %s' % key) from None
def _append_message(self, message):
"""Append message to mailbox and return (start, stop) offsets."""
@@ -1572,7 +1572,7 @@
try:
self._date = float(date)
except ValueError:
- raise TypeError("can't convert to float: %s" % date)
+ raise TypeError("can't convert to float: %s" % date) from None
def get_info(self):
"""Get the message's "info" as a string."""
diff --git a/Lib/multiprocessing/context.py b/Lib/multiprocessing/context.py
index 623f6fb..a3d491b 100644
--- a/Lib/multiprocessing/context.py
+++ b/Lib/multiprocessing/context.py
@@ -189,7 +189,7 @@
try:
ctx = _concrete_contexts[method]
except KeyError:
- raise ValueError('cannot find context for %r' % method)
+ raise ValueError('cannot find context for %r' % method) from None
ctx._check_available()
return ctx
diff --git a/Lib/multiprocessing/pool.py b/Lib/multiprocessing/pool.py
index a545f3c..c2364ab 100644
--- a/Lib/multiprocessing/pool.py
+++ b/Lib/multiprocessing/pool.py
@@ -720,14 +720,14 @@
item = self._items.popleft()
except IndexError:
if self._index == self._length:
- raise StopIteration
+ raise StopIteration from None
self._cond.wait(timeout)
try:
item = self._items.popleft()
except IndexError:
if self._index == self._length:
- raise StopIteration
- raise TimeoutError
+ raise StopIteration from None
+ raise TimeoutError from None
success, value = item
if success:
diff --git a/Lib/multiprocessing/process.py b/Lib/multiprocessing/process.py
index bca8b7a..37365f2 100644
--- a/Lib/multiprocessing/process.py
+++ b/Lib/multiprocessing/process.py
@@ -199,7 +199,7 @@
try:
return self._sentinel
except AttributeError:
- raise ValueError("process not started")
+ raise ValueError("process not started") from None
def __repr__(self):
if self is _current_process:
diff --git a/Lib/netrc.py b/Lib/netrc.py
index bbb3d23..aa8eea3 100644
--- a/Lib/netrc.py
+++ b/Lib/netrc.py
@@ -26,7 +26,7 @@
try:
file = os.path.join(os.environ['HOME'], ".netrc")
except KeyError:
- raise OSError("Could not find .netrc: $HOME is not set")
+ raise OSError("Could not find .netrc: $HOME is not set") from None
self.hosts = {}
self.macros = {}
with open(file) as fp:
diff --git a/Lib/nntplib.py b/Lib/nntplib.py
index 28cd099..5961a28 100644
--- a/Lib/nntplib.py
+++ b/Lib/nntplib.py
@@ -866,7 +866,7 @@
try:
[resp_num, path] = resp.split()
except ValueError:
- raise NNTPReplyError(resp)
+ raise NNTPReplyError(resp) from None
else:
return resp, path
diff --git a/Lib/pickle.py b/Lib/pickle.py
index 702b0b3..faa8fd7 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -269,7 +269,7 @@
obj = getattr(obj, subpath)
except AttributeError:
raise AttributeError("Can't get attribute {!r} on {!r}"
- .format(name, obj))
+ .format(name, obj)) from None
return obj, parent
def whichmodule(obj, name):
@@ -919,7 +919,7 @@
except (ImportError, KeyError, AttributeError):
raise PicklingError(
"Can't pickle %r: it's not found as %s.%s" %
- (obj, module_name, name))
+ (obj, module_name, name)) from None
else:
if obj2 is not obj:
raise PicklingError(
@@ -964,7 +964,7 @@
except UnicodeEncodeError:
raise PicklingError(
"can't pickle global identifier '%s.%s' using "
- "pickle protocol %i" % (module, name, self.proto))
+ "pickle protocol %i" % (module, name, self.proto)) from None
self.memoize(obj)
diff --git a/Lib/shutil.py b/Lib/shutil.py
index bd4760f..31536fe 100644
--- a/Lib/shutil.py
+++ b/Lib/shutil.py
@@ -786,7 +786,7 @@
try:
format_info = _ARCHIVE_FORMATS[format]
except KeyError:
- raise ValueError("unknown archive format '%s'" % format)
+ raise ValueError("unknown archive format '%s'" % format) from None
func = format_info[0]
for arg, val in format_info[1]:
@@ -962,7 +962,7 @@
try:
format_info = _UNPACK_FORMATS[format]
except KeyError:
- raise ValueError("Unknown unpack format '{0}'".format(format))
+ raise ValueError("Unknown unpack format '{0}'".format(format)) from None
func = format_info[1]
func(filename, extract_dir, **dict(format_info[2]))
diff --git a/Lib/sysconfig.py b/Lib/sysconfig.py
index 9314e71..ed0a34d 100644
--- a/Lib/sysconfig.py
+++ b/Lib/sysconfig.py
@@ -147,7 +147,7 @@
try:
return s.format(**os.environ)
except KeyError as var:
- raise AttributeError('{%s}' % var)
+ raise AttributeError('{%s}' % var) from None
def _extend_dict(target_dict, other_dict):
target_keys = target_dict.keys()
diff --git a/Lib/warnings.py b/Lib/warnings.py
index 5badb0b..d7d88d3 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -209,7 +209,7 @@
if lineno < 0:
raise ValueError
except (ValueError, OverflowError):
- raise _OptionError("invalid lineno %r" % (lineno,))
+ raise _OptionError("invalid lineno %r" % (lineno,)) from None
else:
lineno = 0
filterwarnings(action, message, category, module, lineno)
@@ -233,7 +233,7 @@
try:
cat = eval(category)
except NameError:
- raise _OptionError("unknown warning category: %r" % (category,))
+ raise _OptionError("unknown warning category: %r" % (category,)) from None
else:
i = category.rfind(".")
module = category[:i]
@@ -241,11 +241,11 @@
try:
m = __import__(module, None, None, [klass])
except ImportError:
- raise _OptionError("invalid module name: %r" % (module,))
+ raise _OptionError("invalid module name: %r" % (module,)) from None
try:
cat = getattr(m, klass)
except AttributeError:
- raise _OptionError("unknown warning category: %r" % (category,))
+ raise _OptionError("unknown warning category: %r" % (category,)) from None
if not issubclass(cat, Warning):
raise _OptionError("invalid warning category: %r" % (category,))
return cat
diff --git a/Lib/xml/dom/xmlbuilder.py b/Lib/xml/dom/xmlbuilder.py
index e9a1536..60a2bc3 100644
--- a/Lib/xml/dom/xmlbuilder.py
+++ b/Lib/xml/dom/xmlbuilder.py
@@ -80,7 +80,7 @@
settings = self._settings[(_name_xform(name), state)]
except KeyError:
raise xml.dom.NotSupportedErr(
- "unsupported feature: %r" % (name,))
+ "unsupported feature: %r" % (name,)) from None
else:
for name, value in settings:
setattr(self._options, name, value)
diff --git a/Lib/xml/etree/ElementPath.py b/Lib/xml/etree/ElementPath.py
index ab6b79a..361f6d5 100644
--- a/Lib/xml/etree/ElementPath.py
+++ b/Lib/xml/etree/ElementPath.py
@@ -80,7 +80,7 @@
raise KeyError
yield token[0], "{%s}%s" % (namespaces[prefix], uri)
except KeyError:
- raise SyntaxError("prefix %r not found in prefix map" % prefix)
+ raise SyntaxError("prefix %r not found in prefix map" % prefix) from None
else:
yield token